Process for manufacture of viscous polymers



J. A. REID MarchSO, 1943.

PROCESS FOR MANUFACTURE OF VISCOUS POLYMERS found .that the mo1eou1ar weight distribution.

` "probability curve.

Patented Mu. ao, 1943 s PATENT vorluct;

raooEssfioamNUFAorUnE'or viscous Aromanticas o 'James A."r"lteil,vBartlesville, Okla., assigner to Phillips vPetroleum Company, a corporation of Delaware Application Moron 3, '1941, serial No. 381,565

- 11 claims. '(01. 19e-10) This invention relates to the manufacture of oils from hydrocarbons of lower molecular weight, and more speciiically tothe production of oils within a selected range of molecular weights through the controlled reaction of olens and their polymers. e

It has hitherto been proposed that oleiins be subjected to the action of catalysts for the production of oils such as are suitable for use in lubricants. The olefin charge stocks for the manufacture of such oils include normally gaseous oleiins and olefns of higher molecular weight, such as those from dehydrogenated naphthas and waxes, cracked distillates, and similar products, either in relatively pure states or admixed with inert diluents. Metal halide catalysts such as aluminum chloride and lbromide, boron iluoride, zirconium chloride and bromide, titanium chloride, and the like, are preferred catalysts r.for use in such processes, although no particular oneis the .full equivalent of any other, and other catalysts may, at times, also be used.

.- I have found that the molecularA weights and viscosities of the hydrocarbon products resulting from a reaction of olens under .particular conditions 4in these systems vary widely.' vI have also of products from suitable polymerization systems may be represented by means of an arithmetic In general, at the lower reaction temperatures the average `molecular weight ,of the product is higher, and the proportion of very high molecular weight -viscous oil is increased. At higher reaction temperatures, the proportion of very high molecular weight polymer is reduced, and the proportion of polymer of low molecular weight and viscosity is increased. As a consequence, the proportion of polymer in a v polymerization product within a selected range of molecular weight is relatively small. For eX- ample, from twenty to fty per cent of the polymers are normally within the r-ange od viscosity making them suitable for use in the preparation discussed, that a-.favorable yield of hydrocanbons within a desired and preselected range of viscosity issecured, the separation o1' the desired I,products and the recycle of the polymers oi higher and/or lower viscosities 'for lfurther conversion with a dresh charge stock to form additional products in the desired range.

I have now discovered that after removal from the total product mixture, of the fraction or fractions which constitute the desired product, the remaining simple polymer fractions of both lower and higher molecular weights, or viscosities, may be returned to the polymerization step for conversion with added monomeric olens to form a product containing substantially the same proportion of desired viscous fractions as existed in the first polymer mixture. In this manner, substantially complete conversion of low boiling olefins to polymers within a preselected range of viscosity is secured by the multiple recycle of imdesired heavy, as well as light, polymer fractions with added increments of monomeric olefin. This yselective conversion has 'been elucidated in part by the discovery that in a system for the preparation of intermediate and higher viscosity polymers, lower viscosity polymers as well as monomeric olens undergo polymerization to intermediate and -higher viscosity polymers, and that in a system for preparation oi' intermediate viscosity polymers, higher viscosity polymers undergo some sort of concomitant reaction to form desirable products of intermediate viscosity. The simultaneous occurrence of these two types of reactions yields an apparent conversion of monomeric olen in a mixture of polymers of relatively high and low viscosity to products within the viscosity range desired.

It is an object of my invention to provide a process whereby olefins are converted predominantly to products within a preselected range of molecular weight.

Another object of this invention is to convert olens to valuable polymers without the formation of undesired products.

A more specic object of this invention is to provide a process for converting olens to polymers having properties which make them suitable for fuse in the preparation of lubricants.

Other objects and advantages of my invention will be seen from the accompanying disclosure and discussion. i

The yield of desired product fraction from a single batch or portion of composite product is dependent principally on the limits of the desired molecular weight 'or viscosity range and the confrom 60 to 90 per cent, oi the olefin charge mayA then be ultimately converted to hydrocarbons within the preselected range of molecular weight. Many polymerization catalysts can be usediunder conditions such that the reaction promoted is essentially one of simple polymerization, uncomplicated by side reactions, or secondary re actions, such as molecular rearrangements, cyclization, hydrogenation-dehydrogenation, and the like. Such catalysts and conditions are to be preferred.

When some olefin :polymerization catalysts such as zirconium tetrachloride are used the conditions. under which a total polymer product with a molecular weight distribution which follows an arithmetic probability curve is formed, cover a rather wide range, while with other olefin polymerization catalysts which .tend toy form nonaliphatic or cyclic products such as aluminum chloride, the range of polymerization conditions, within which substantially aliphatic polymers are formed with a molecular weight distribution which kfollows an arithmetic probability curve, are much more` limited. I prefer to operate the polymerization step of my process with such a polymerization catalyst and withinv such a range of polymerization conditions that a substantial proportion of a viscous polymeric product will be produced which will have a molecular weight distribution which can be represented by an arithmetic probability curve. When using those catalysts for which only a narrow range of polymerization conditions will produce such products, it may be found that conditions somewhat to one side `or the other of this range will produce appreciably larger yelds of desired product with only small yields of undesired products. The practice of my invention with such polymerization conditions, with suitable treatment of recycled material to remove undesired material is contemplated.

Although the products of such side or secondary reactions tend to build up in arecycle system such as the one herein disclosed,v when the conditions are such that .these take place to only a limited extent such products will be contained to a small extent in the desired fraction recovered as a product ofthe process, and their removal in this manner will often keep them from building up within the system to excessive amounts. However, if it is found lexpedient for other reasons to operate with catalysts, or under conditions, such that larger amounts ofy these less desirable materials are formed, the recycle stream or streams may be treated to remove all or most of these materials and thus prohibit or limit their accumulation within the system. f

The reactions are usually performed most satisfactorily within the temperature range of about 30 to 215 F., although temperatures as high as' 300 F. or as low as 120 F. may'be used for the conversion of particular olens or the production of special products. Suiilcient pressure should be maintained in the system to keep the catalyst and the reacting hydrocarbons substantlally in liquid phase. It is desirable in most cases to y provide suillcient catalyst concentration and contact time that a predominant proportion of the olefin charge becomes converted. This time may vary from a half hour or less to a period of six to fifteen hours with the higher molecular weight straight chain olefns.

The method used for segregating the desired product fraction is dependent upon the'characteristics of the polymer. Distillati'on, selective solvent extraction or adsorption, limited selective addition or conversion reactions, and so forth, are useful in particular applications. In the production of lubricating oils, for example, the low molecular weight polymers may be very satisfactorily removed by fractional distillation at reduced pressure. Some of the lubricant fractions may be distilled at reduced pressure, leaving a viscous residue. In other cases it is desirable to separate the less viscous or lower molecular weight polymersby selective extraction or adsorption. I

'I'he reaction product in the desired viscosity range which has been separated from the product mixture may subsequently be subjected to additional treatment to convert it into a more useful product. In general, it may be used as a charge stock for synthesis of a wide variety ol.' derivatives and synthetic chemicals. For use as a component of a lubricating oil, it is usually desirable to hydrogenate the desired product fraction to increase its stability toward oxidation, the conditions of hydrogenation being so adjusted that substantial decomposition is not produced. The hydrogenated oil may be blended with various other stocks, or further treated by a selective separation step, such as distillation. To the hydrogenated product may be added other synthetic or natural oils, wear control agents, oxidation and sludge inhibitors, and the like.

Simple polymers of somewhat lower molecular weight than that suitable for the direct manufacture of lubricants may be employed to alkylate aromatic hydrocarbons, such as benzene or toluene, or their derivatives to form oils of high solvent capacity, using catalysts such as sulfuric acid, hydrouoric acid, aluminum chloride and other metal halide catalysts.

'I'he drawing which forms a part of this speciiication, represents schematically a preferred arrangement of apparatus for'the production of selected viscous hydrocarbons according to one modification of the present invention.

Referring now to the drawing, an'olenic hydrocarbon material is introduced into the system through pipe I0 and valve II, either in a pure state or in admixture with a low boiling nonreactive diluent such as a paraffin hydrocarbon. When such oleflns are produced by dehydrogenation they will generally be accompanied by at least a certain amount of the unreacted parains. The charge stock, comprising such fresh olefins together with heavy recycledsimple olen polymers, and if desired similar light polymers as will be discussed more fully, is passed by pump I2 preferably through valve I3 to dehydrator or purier I4, and thence through pipe I6 and valve I5 to polymerizer or reactor 20. Ii' it is' unnecessary or undesirable in any particular instance to use the purifier I4, it may be by-passed through pipe I 'I and valve I8.

From pipe I6 the charge is admitted to polymerizer or reactor 20, with or without preheating or other temperature adjustment as may be found necessary or desirable, 4wherein it is contacted with a suitable metal halide catalyst. When a large kettle-like reactor is used, such as the one diagrammatically illustrated, the catalyst may be introduced from any desirable source through means such as pipe 2i, controlled by valve 22, as a solid, liquid, or gas, as the case may be, and in solution or suspension in an inert material 'when such is desirable. The reacting mixture is vigorously agitated, as by the paddles 23, and heat of reaction is preferably removed and the temperature controlled by circulating a cooling medium through coil 24. The reactor is preferably not maintained liquid full, although the reaction should be carried out in liquid phase with amajor part of the reactant and reacting hydrocarbons present as a liquid. Sincev the desired viscous product has practically a negli,- ble vapor pressure at the reaction temperature, sufiicient low boiling inert material such as propane, butane, or pentane, ory the like should be present to maintain in the reactor a positive pressure with respect to the atmosphere, and such material may be separately added, or removed, during the reaction throughl valve in pipe 26.

A stream of the reacted material, with the catalyst in suspension or solution, is passed from rcactor 20 through pipe 30 and valve 3| to the catalyst separator 32, wherein a major portion of the catalyst is separated from the hydrocarbon material, and can be discharged from the system through pipe 33 and valve 34, or returned wholly or in part to the reactor 20 through pipe 35 and valve 36. The actual type andmanner of separation 'effected in separator 32 will be determined by the catalytic material employed to effect the polymerization. When using a catalyst such as zirconium tetrachloride, the catalyst may be ltered from the hydrocarbon material in which it is suspended by simple means. adapted to such materials, and the catalyst, associated if desired with a small amount of hydrocarbon material to form a slurry, can be returned at least in part to reactor 20 through pipe 35. Whenv using a relatively volatile metal halide catalyst such as boron uoride, tin tetrachloride, or titanium tetrachloride, or the like, it mray be separated by distillation from the heavier hydrocarbon, and returned to the reactor as indicated. -Light hydrocarbons separated along with such Volatile catalyst may be returned to the reactor along with the catalyst, or may be discharged from the system through means not shown. The functions of the separator 32 may also include means for treating sludged catalysts, or those in other inactive forms, or such materials may be removed through pipe 33.

After separation of the major part of the Acatalyst, the hydrocarbon material is passed through pipe 31 and valve 38 to scrubberv 40, wherein it is subjected to a treatment for removing remaining traces of catalyst and any acid material, as by washing with an alkaline solution, or treatment with a solid material such as soda ash or the like. Such material may be introduced through pipe 4i and valve 42, and the solutionl and such impurities, or reaction products thereof, removed through pipe 43 and valve 44. The purified hydrocarbon material is then passed through pipe 45 and valve 46 to fractionating means 50, which may consist of a simple fractionating column, with suitable bubble trays, heating means for the bottom and cooling and refluxing means for the top, or somewhat more complex fractionating equipment if the circumstances demand it. The

principal material removed comprises essentially low boiling, relative inert material which is not preferably directly recycled to the reactor, such as light paramn hydrocarbons, and is removed as an overhead product through pipe 5I and valve 52. The residual material, consisting principally of heavy hydrocarbons formed in the polymerization step, is passed through pipe 53 and valve 54 to fractionating means- 55, which may be a simple fractionating column or a more complex combination of equipment as discussed in connection with fractionating means 50. From the hydrocarbon material passed to fractionating means 55 is separated a light hydrocarbon fraction comprising hydrocarbons produced in the polymerization step and having molecular weights, or viscosities, too low to be included in the lubricating range product. This light product is passed as a distillate fraction through pipe 56 and valve 51 by pump 58 to storage and/or treating means 66. The residue, which contains the desired product along with heavier material, is passed through pipe 16 and valve 1| to fractionating means 12, which may also be simple or consist of combined equipment, as is necessary. The desired hydrocarbon product, comprising one or moie hydrocarbon fractions produced by polymerization in reactor 20 and having viscosities and viscosity characteristics in the range desired for the product of the process, is removed as a distillate product through pipe 13 controlled by a valve 14, and is passed by pump 15 to separator or storage means 16,

The fractionations in means 55 and 12 are preferably carried out at relatively low pressures and preferably, especially in 12, at subatmospheric pressures. This may be facilitated by means of suitable pumping equipment, illustrated by pumps 58 and 15, and may be accompanied by steam distillation or the like, as by the injection of steam into the fractionating means 12 through pipe 11 and valve 18. In such a case, a separation between condensed water and oil takes place in separator 16, and Water is Withdrawn through pipe 80 and valve 8|, while the desired hydrocarbon material is withdrawn through pipe 82 and valve 83.

A residual hydrocarbon fraction, containing olefin polymers too heavy or viscous for inclusion in the desired product, is recovered. from a low point of fractionating means 12, and is passed through pipe 85 and valve 86 by pump 81 to storage and/or treating means 90. This separation of desired product from the residue may be accomplished in some instances more advantageously through the use of selective solvents, selective adsorbents, or by a selective reaction and segregation of the reaction product.

As previously discussed, the hydrocarbon material produced by polymerization oi simplevolens in the presence of a catalyst such as zirconlum tetrachloride is almost entirely composed of simple olefin polymers. In such cases the st'orage and treating means 60 and 90 will serve primarily as storage, and the material passing through pipes 56 and/or B8 can be returned to the polymerization with little, if any additional treatment. Thus light polymers separated through pipe 56 are passed from 60 through pipe 6| to polymerizer 20 either through valve 62 to pipe I0 or through pipe 59 and valve 69 to pipes i1 and i6, and heavy, viscous polymers separated as residual material through pipe 88 are passed from 90 through pipe 9| to polymerizer 20 either through valve 92 to pipe i8 or thrcugh pipe 91 and valve 98 to pipes i1 and i6. However in many cases `when a catalyst such as aluminum chloride is used, especially at 'somewhat elevated temperatures, a certain4 amount of hydrocarbon material other than simple olefin polymers is pro'y duced by side reactions such as cyclization, isomerization, and the like, aspreviously mentioned. In order to realize the greatest benefits from my invention it is more desirable that the recycle material comprise essentially simple olcn polymers, and in such cases the lrecycle material should be treated to remove at least an appreciable part of the hydrocarbonsthat arenot simple olefln polymers. Such treatment is included in the function of treating means 60 and 90, and inmost instances consists of a selective solvent extraction adapted to'separate cyclic hydrocarbons from ali` phatic hydrocarbons. The purified simple olefin polymer's'are then passed to reactor 20, while the hydrocarbons removed therefrom are separated from the process, as through pipe 88 and valve 88, and/or through pipe 88 and valve 98. At

' times, when the production of such undesirable material is not great, effective control of its concentration'may be carried out by recycling only a portion of the light or heavy hydrocarbon material, discharging from the system another portion, Other means may bel determined by trial and applied by one skilled in the art for any particular modification. If the viscous hydrocarbon residue passing through pipe 88 contains heavy sludge, or the like, -this material should be removed even when simple olen polymers are' stocks for this system include the aliphatic olens which contain three or more carbon-atoms per molecule. to reaction, so that reaction conditions which will cause it to react generally also promote an undue formation of hydrocarbons which are not simple olefin polymers, although with some catalysts `it enters into reaction to form such desirable hydrocarbons if other low boiling olefins are also present and reacted. The olens may be obtained in a relatively pure state by dehydration of the appropriate alcohols, dehydrogenation of the cor-V responding parafiins, depolymerization or cracking of heavier olens or polymers from another process, or the like. On a commercial scale, the oleilns are preferably manufactured by dehydrogenation of paraffin hydrocarbons. The lower boiling oleilns such as propylene and isobutylene may be prepared by thermal or catalytic treatment of corresponding paraiiin hydrocarbons, while higher molecular weight olens may be prepared either by thermal treatment of paraflins to produce lighterv oleiins or by catalytic dehydrogenation of higher paramns, such as those'found in naturall gasoline, with the formation of olens having predominantlythe same number of carbon atoms in the molecule as the original paraillns. Selected fractions of olefin-containing refinery products, such as the products from cracking stills, may also be used as charge stocks.

I have` found that ther presence in the charge stock of moisture, most oxygen compounds, such as alcohols and ethers, sulfur compounds'such as mercaptans and thiophene, alkaline nitrogen compounds, and in some cases compounds conv taining halogens, tend to deactivate the catalyst Ethylene is generally quite resistant and promote undesirable side reactions, so as to alter adversely the characteristics, quality, and yield of the vdesired product. The substantial absence of these compounds from the charge mixture is essential to continued satisfactory operation of the process, so that in most cases it will be necessary to use some means such as purifier il. The polymerization of oleiins in my process is also to be performed in the substantial absence of added aromatic hydrocarbons. The dioleilns such as butadiene are also undesirable in the charge stock, and other nonolenicunsaturates should also be removed. 'I'he operation oi' purifier I4 will depend toa certain extent upon the contaminant which is to be removed. When the charge stock is produced by dehydrogenation, it may contain traces of diolens or acetylenes which can bel removed by mild polymerizing agents, such as dilute mineral acids, fullers earth, bauxite, etc. Adsorbents, such as dehydrated bauxite, silica gel, activated charcoal, etc. may be used to remove many sulfur compounds, water, alcohols, ethers, and the like. With some sulfur compounds, decomposition may be a part of the removal, followed by removal of hydrogen sulfide, or similar product, by appropriate means. Halogen compounds may also be removed by adsorption, or by chemical reaction. The specific process to be used for any particular situation can be readily determined by trial, and applied, by one skilled in the art.

Many variations in the apparatus or operation of this process may be desirable in specific embodiments. Two or more reactors may be used, or onlya single one as shown may be used. A volatile diluent may be evaporated from the reaction mixture to aid in the control of the reaction temperature. If desired tube coil reactors may be used, with suitable apparatus or flow for maintaining an intimate association of catalyst and reactants, and for effecting a continuous physical removal of the catalyst from the eiiiuent with recycle of a part or portion of it as shown. Light oleflnlc products may be removed directly, by additional means not shown, from fractionating means 55,' or through pipe 65, as the source of hydrocarbons possessing veryv speciflc properties. I

'I'he following examples are given-to indicate application of this process. Any specific limitations of conditions which are recited are not necessarily to be construed as indicating limitations of my invention.

Example L Isobutylene dissolved in isobutane as diluent, together with recycled polymer, was charged as a liquid to a reactor containing zirconium tetrachloride catalyst. The reacting mixture was agitated for approximately 11/2 hours, while the temperature was maintained at about F. The product was withdrawn from the reactor through alter which retained most of the catalyst in the reaction chamber for further use. After the product had been washed with a hot caustic solution to remove traces of catalyst and acidic materials, it was placed in a distillation apparatus and the isobutane diluent was removed. I'he polymers boiling below635 F. were fractionated from the residue at reduced pressure and were returned to the polymerization reactor. The polymer boiling between 635 F. and approximately 1020 F. (corrected 'to N. T. P.) was distilled at low pressure with vthe aid ofl steam, leaving a viscous residue which was'returned for reaction with additional isobutylene. The selected intermediate vacuumand steam-distilled polymer fractio constituting about 30 per cent of the polymer l ture. was then hydrogenated to yield a base stock for lubricating oils in the SAE 30 viscosity range. 'Ihrough recycle of the polymers boiling below 635 F. and above 1020 F. (corrected to normal temperature and pressure), a total of about 75 per cent by weight ofthe isobutylene charged was ultimately converted to the desired product.

Example II The olens containing six and more carbon atoms per molecule, resulting from dehydrogenation of a natural gasoline containing predominantly hexanes, heptanes, and octanes, may be polymerized with both light and heavy recycled merization reactor, together with the polymer boiling below 500 4F. The temperature of the liquid-is not permitted to exceed 185 F. in the distillation until substantially all of the titanium tetrachloride had been distilled. The polymer boiling between 500 and 670 F. (N. T. P.) is segregated ioruse in alkylating an aromatic hydrocarbon. The residue is separated by distillation at low pressure with steam 'into a fraction for use-in a lubricant blend, and a'residue, part of which is returned for reaction in the polymerization reactor. A part oi the residual product is used, after hydrogenation, as a blending agent. Approximately 80 per cent of the olen is ultimately-converted to useful product in this process. A

These examples are here recorded to illustrate speciiic applications of my process and do not necessarily limit its scope of applicability. Y

polymer in liquid phase at about 160 F. and a is also recycled to the polymerization reactor for conversion. The SAE 60 oil is hydrogenated and blended with anti-oxidants and wear-control agents. The resultant product which is obtained in 65 per cent yield is very resistant to decomposition or formation of residue in use as an aircraft engine lubricant.

A mixture of olens and paraii'ins containing nineto fourteen carbon atoms `per molecule which result from dehydrogenation of a waxy petroleum distillate, from which the dioleiins have been removed, together with recycled polymer, may be treated in liquid phase at about 185 F. with zirconium chloride. The polymerization is permitted to proceed for about iive hours, until substantially all df the charge has become polymerized. After separation of the catalyst and acidic materials, the parailinic diluent is distilled from the polymer. The polymers boiling below about 600l F. (corrected to normal temperature and pressure), distilled at reduced pressure, are hydrogenated to make a component of a lubricating oil, while higher boiling polymers are returned to the polymerization step along With fresh charge.

Example IV A solution of pentenes and hexenes in paraffin hydrocarbons of corresponding boiling range is mixed with ten per cent titanium tetrachloride at about 140 F. After about three hours the product and catalyst are removed from the reactor. The paraiiin hydrocarbons are removed by distillation at slightly reduced pressure, maintaining the residue at a temperature not in excess of about 170 F. The pressure is then reduced somewhat further and the titanium tetrachloride is distilled oi and returned to the poly- I claim: 1. A process for the polymerization of olens to form viscous hydrocarbons within a preselected range of viscosity and adapted for use in the preparation of lubricating oils, comprising reacting anoleiln hydrocarbon comprising monomeric oleiins in the presenceof a metal halide polymerization catalyst under suitable conditions of pressure, temperature and contact time to yield a product containing relatively viscous polymers, said temperature lying within the range of 30 to 215" F., separating from the catalyst eilluent hydrocarbons in said preselected viscosity range, separating also polymers having lower and higher viscosites, and returning said polymers of lower and higher viscosites for reaction with additional amounts of said olen charge under the original conditions of reaction to :form

. additional material within the selected range of viscosity.

2. A process for the conversion of oleiins to viscous polymers suitable for use in the preparation of lubricating oils and boiling between 635 and 1020 F. (corrected to N. T.`P.), comprising reacting an oleiin hydrocarbon comprising monomeric olens in the presence of a metal halide polymerization catalyst at a temperature between 30 and 215 F., and under sucient pressure to maintain thel reactants substantially in liquid phase, for a time suicient to eiect a major conversion of monomeric olens to yield a product containing viscous polymers in a desired viscosity range and boiling between 635 and 1020 F. (corrected to N. T. P.), separating from the effluent of the catalystA polymers in said desired range and removing the same from the process, separating also polymers of lower viscosites and polymers of higher viscosites, and returning said polymers of lower and higher viscosites for reaction with additional amounts of said olefin charge under the original conditions of reaction to form additional material within the desired range.

3. A process for the conversion of normally gaseous monomeric olefins into polymers within a preselected range of viscosity and adapted for use in the preparation of lubricating oils, comprising reacting a charge comprising said olefin hydrocarbons in the presence ofA a metal halide polymerization catalyst, capable of polymerizing olens to form aliphatic polymers having viscosity characteristics of lubricating oil, under suitable conditions of pressure, temperature and contact time to yield a product containing relatively viscous polymers, said temperature lying within the range of to 185 F., separating from the catalyst enluent viscous polymers in a desired viscosity range, sepa-rating also polymers having lower and higher viscosities, and returning said polymers of lowerand higher viscosities for reaction with additional amounts of said normally gaseous` olefin chargeV under the original conditionsofreaction to form additional material within the selected range of viscosity.

'4. A process for the conversion of oleiins intol viscous polymers within a preselectedviscosity range and adapted for use in the preparation of lubricating oils,-comprising reacting an olefin charge comprisingV monomeric oleiins in the presence of a zirconium tetrachloride catalystat a ,y

temperature between about 30 and 215 F., under suillcient pressure to maintain the reactants substantially in liquid phase and for a time sufficient to eifect a conversion of a major part of monomerio olefin to yield a product containing viscous polymers a substantialpart of which are in said preselected viscosity range, separating from the catalyst emuent polymers in said preselected.

viscosity range, separating also simple olen polymers of higher and lower viscosities, and return-T ing said simple olefin polymers of lower and high-l er viscositiesV for reaction with additional lamounts of said olefin charge under'the original conditions of reaction to form additional hydrosufficient pressure to maintain the reactants substantially in liquid phase and for a time suiilcient,

to effect a conversion of a major part of monomeric oleiln to yield a product containing visin 'said preselected viscosity range, separating from the catalyst 'eiiiuent polymers in said preselected viscosity range, separating also simple olefin polymers of higher and lower viscosities and returning said simple olefin polymers of lower and higher viscosities for reaction with additional amounts of said olen charge under cous polymers a substantial part of which areV the original conditions of reaction to'form additional hydrocarbons within said preselected range.

6. A process for the polymerization of olefin hydrocarbons into avviscous hydrocarbon fraction adapted to be va componentof a lubricating oil, which comprises polymerizing a low boiling monomeric oleiln hydrocarbon material in the presence of a zirconium tetrachloride catalyst at a temperature between 30 and 215 F., under a pressure suiilcient to maintain the hydrocarbon material substantially in liquid phase and for a period of time sumcient to form viscous polymers a substantial part of which are within a viscosity range suitable for a component of lubricating oil, Y

separating from the catalyst efiluent a hydrocarbonfraction comprising said polymers and removing same from the process, separating also a -hydrocarbon fraction'comprising lower viscosity .polymers and a hydrocarbon fraction comprising higher viscosity polymers, and admixing at least portions of both said fractions with said low boiling monomeric olefin hydrocarbon material charged to the process.

7. .A process for the polymerization of olefin hydrocarbons into a viscous hydrocarbon fraction adapted to be a component of a lubricating oil, which comprises polymerizing a low boiling monomeric olefin' hydrocarbon material in the presence of an aluminum chloride catalyst at a temperature between 30 and 215 F., under a pressure suiiicient to maintain the hydrocarbon material substantially in liquid phase and for a period of time suillcient to form viscous polymers a substantial part of lwhich are'within a viscosity rangesuitable for a -component of lubricating oil. separating from the catalyst eiliuent a hydrocarbon fraction comprising said polymers and removing same from the process, separating also a hydrocarbon fraction comprising lower viscosity polymers and a hydrocarbon fraction comprisingv higher viscosity polymers, and admixing at least portions of both. said fractions with said low boiling monomeric olefin hydrocarbon material charged to the process.

8. The process for the polymerization -of low boiling monomeric oleilns to polymers within a limited viscosity range and suitable foruseas a lubricating oil stock, which comprises polymerizing said oleilnsin liquid phase in the presence of a metal halide polymerization catalyst under such conditions as to produce therefrom viscous polymers having a molecular weight distribution which substantially follows an arithmetic probability curve, separating from hydrocarbon material eiiluent from said polymerization a fraction within said limited viscosity range so produced and removing same from the process, separating `also from said hydrocarbon effluent polymer fractions having viscosities above and below said limited viscosity range, and returning said lastnamed polymer fractions to said polymerization in admixture with additional amounts of said low boiling monomeric oleilns..

9. The process for the polymerization of low boilingmonomeric oleilns to polymers within a limited viscosity range and suitable for use as a lubricating oil stock, which comprises polymerizing said olens in liquid phase in the presence of a zirconium tetrachloride polymerization catalyst under such conditions as to produce therefrom viscous polymers having a molecular weight distribution which substantially follows an arithmetic probability curve, separating from hydrocarbon material eilluent from said polymerization a fraction within said limited viscosity range so produced and removing same from the process, separating also from said hydrocarbon eiliuent polymer fractions having viscosities above and below said limited viscosity range,` and returning said last-named polymer fractions to said polymerization in admixture with additional amounts of said low boiling monomeric oleflns.

10. The process for the polymerization of low boiling monomeric oleiins to polymers within a limited viscosity range and suitable for use as a lubricating oil stock, which comprises polymerizing said oleflns in liquid phase in the presence of an aluminum chloride polymerization catalyst under such conditions as to produce therefrom viscous polymers having a molecular weight distribution which substantially follows an arithmetic probability curve, separating from hydrocarbon materiaI eiiluent from said polymerization a fraction within said limited viscosity range so produced and removingsame from the process, separating also from said hydrocarbon eiiluent polymer fractions having viscosities above and below said limited viscosity range, and returning saidlast-named polymer' fractions tov said polymerization yin admixture with additional amounts of said low boiling monomeric oleilns.

metic probability curve, separating from hydro- 10 carbon material eilluent from said polymerization a. fraction within said limited viscosity range so produced and removing same from the process, separating also from said hydrocarbon eiuent polymer fractions having viscosities above and below said limited viscosity range, and returning said last-named polymer fractions to saidl polymerization in admixture with additional amounts of said low boiling monomeric olens. .JAMES A. REID. 

